Agentic Software Engineer (OpenAI Codex) - Remote - USA

About FullStack
FullStack is one of the fastest-growing software consultancy companies in the Americas. We deliver transformational digital solutions to top global companies and Silicon Valley startups. As an employee-first company, we focus on hiring the most talented software designers and developers by creating a positive, respectful, and supportive work environment where they can achieve their greatest potential.
We’re Most Proud Of

• Offering life-changing career opportunities to talented software professionals across the Americas.
• Building highly-skilled software development teams for hundreds of the world’s greatest companies.
• Having delivered hundreds of successful custom software solutions, which have positively impacted the lives and careers of millions of users.
• Our 4.2-star rating on GlassDoor.
• Our client Net Promoter Score of 68, twice the industry average.

The Position
We're Looking To Hire An Agentic Software Engineer (OpenAI Codex-focused) To Join Our Team. You'll Work With Our Incredible Clients In One Of Two Ways

• Team Augmentation: You will integrate directly into our client's team and work alongside their existing designers and engineers daily.
• Design & Build: You will work on a FullStack product team to build and deliver a product to our clients.

What We're Looking For

• 5+ years of professional software development experience with a deep understanding of full-stack architectures (e.g., Java, Python, C#, React, Node, etc.).
• Advanced English is required.
• Successful completion of a four-year college degree is required.
• Deep experience using OpenAI Codex as a primary development environment to coordinate AI-driven implementation across large, multi-file systems while maintaining architectural oversight.
• Experience delivering production software where AI systems generate the majority of implementation code.
• Strong context engineering skills, including structuring codebases, specifications, and documentation to produce reliable, context-efficient AI output.
• Ability to translate complex product requirements into machine-executable, AI-friendly specifications.
• Experience designing AI-first development workflows from specification through deployment.
• Ability to systematically improve AI-generated output through structured iteration and feedback loops.
• Comfort working across multiple stacks, using AI to deliver high-quality, production-ready systems.
• Experience operating across frontend, backend, and infrastructure in AI-accelerated environments.
• Disciplined human-in-the-loop review practices, with risk-adjusted validation for high-impact or safety-critical flows.
• Strong curiosity and initiative in evaluating and adopting emerging AI-native engineering practices.
• Advanced understanding of Agile methodologies and Lean principles and participation in team ceremonies as well as asynchronous work.
• Ability to work through new and difficult issues and contribute to libraries as needed.
• Ability to create and maintain continuous integration and delivery of applications.
• Forensic attention to detail.
• A positive mindset and a can-do attitude.
• Experience working on Agile / Scrum teams.
• Meaningful experience working on large, complex systems.
• Ability to take extreme ownership over your work. Every day is a challenge to ensure you are performing to the expectations you and your team have agreed upon.
• Ability to identify with the goals of FullStack's clients, and dedicate yourself to delivering on the commitments you and your team make to them.
• Ability to consistently work 40 hours per week.

What We Offer

• Competitive Salary.
• Paid Time Off (vacation, sick leave, maternity and paternity leave, holidays).
• 100% remote work.
• The ability to work with leading startups and Fortune 500 companies.
• Health, dental, and vision insurance.
• 401(k) w/ 4% match.
• Ample opportunity for career advancement.
• Continuing education opportunities.

FullStack is proud to be an equal opportunity workplace. We are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity, or Veteran status.
Learn more about our Applicants Privacy Notice.
Nice To Have
We’re Seeking Engineers Who Are AI-enthusiastic In Their Workflow. Professional Experience Or Personal Project Work With The Following Is a Significant Plus

• Cursor, Windsurf, or Google Antigravity.
• Claude Code, Gemini CLI, Codex, or Copilot CLI.